Create Apps with Fn

Fn supports grouping functions into a set that defines an application (or API), making it easy to organize and deploy.

Before you Begin

Set aside about 15 minutes to complete this tutorial.
Make sure Fn server is up and running by completing the Install and Start Fn Tutorial.
- Make sure you have set your Fn context registry value for local development. (for example, “fndemouser”. See here.)

As you make your way through this tutorial, look out for this icon: . Whenever you see it, it’s time for you to perform an action.

Create an App

This part is easy, just create an app.yaml file and put a name in it:

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mkdir myapp2
cd myapp2
echo 'name: myapp2' > app.yaml

This directory will be the root of your application.

Create a Root Function and Trigger

The root function will be available at / on your application.

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fn init --runtime ruby --trigger http

Now we have a Ruby function alongside our app.yaml.

Create a Sub Function and a Trigger

Now let’s create a trigger`` at /hello:

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fn init --runtime go --trigger http hello

Now we have two functions in our app–one directly in the root folder and one in the hello folder. If you have the tree utility installed run:

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tree

This will show the structure we’ve created which looks like this:

.
├── Gemfile
├── app.yaml
├── func.rb
├── func.yaml
├── hello
│   ├── func.go
│   ├── func.yaml
│   └── test.json
└── test.json

Deploy the entire app

Now we can deploy the entire application with one command:

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fn deploy --create-app --all --local

Once the command is done we can examine the structure of the myapp2 application. First, get a list of deployed applications. The l or list command, followed by a, app or apps displays the list of applications:

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fn list apps

NAME		ID				
myapp2		01CT77FVBTNG8G00GZJ0000001

You should see myapp2 in the list of deployed applications. We can then list application’s triggers by using the list command, followed by triggers:

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fn list triggers myapp2

FUNCTION    NAME            ID                          TYPE    SOURCE          ENDPOINT
hello       hello-trigger   01CT77HZ2NNG8G00GZJ0000005  http    /hello-trigger  http://localhost:8080/t/myapp2/hello-trigger
myapp2      myapp2-trigger  01CT77FWDFNG8G00GZJ000000   http    /myapp2-trigger http://localhost:8080/t/myapp2/myapp2-trigger

If you have previously set the FN_REGISTRY registry environment variable your Docker image names will be prefixed by it. Otherwise your output will look like:

fndemouser/hello        0.0.2       64049f5cfc52        10 minutes ago      15.6MB
fndemouser/myapp2       0.0.2       f9aebef4821a        11 minutes ago      59.5MB

Once again l is a valid abbreviation for list followed by the object you wish to display, either apps or triggers. We can see there are two triggers fndemouser/hello and fndemouser/myapp2 with two different Docker images associated with them.

Let’s surf to our application. Open in a browser or use curl to call each of the functions.

Root function at: http://localhost:8080/t/myapp2/myapp2-trigger
And the hello function at: http://localhost:8080/t/myapp2/hello-trigger

Wrapping Up

Congratulations! In this tutorial you learned how to group functions into an application and deploy them with a single command.

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